Mr Hele, a question

Great to see those lovely pictures and words about the ‘Rob North’ BSA Rocket 3 in the last issue. It’s good to see an original bike with genuine 19in wheels, forks and period Dunlop tyres.

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The part that interests me is that it was always said that the T150 was made by adding a cylinder onto the company’s ‘current’ 500 twin when the two possibilities were the pre-unit T100 and the unit T100.

The first had 63 x 80 bore and stroke while the latter (which Triumph had enjoyed racing success with) was 69 x 65.5. To me, it seems that the T150 shared its engine dimensions with the humble BSA C15 which was the only engine in the range with 67 x 70 dimensions.

I wonder why Mr Hele didn’t go with the 69 x 65.5 measurements?

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Graham Curtis, Derby

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